Preparation of monohaloacyl halides

ABSTRACT

A process for the preparation of monohaloacyl halides by halogenating ketenes in the presence of a sulfone of the formula   WHEREIN R and R1 are as defined herein.

United States Patent H 1 3,882,173

Gash et al. May 6, 1975 PREPARATION OF MONOHALOACYL Primary ExaminerLorruinc A. Wcinberger U.S. Cl. 2 60/544 Y; 260/544 M Int. Cl C07c 51/58: C07c 53/20 Field of Search 260/544 Y References Cited UNITED STATES PATENTS 4/!959 Erik 260/544 Y 6/1959 Prill 260/544 Y Assistant Examiner-Richard D. Kelly Attorney. Agent or Firm-William l. Andress; John L Young: Donald W Peterson [57] ABSTRACT A process for the preparation of monohnlozicyl halides by hulogenuting ketenes in the presence of a sulfonc of the formula wherein R and R' are as defined herein,

2] Claims. No Drawings PREPARATION OF MONOHALOACYL HALIDES This invention relates to the preparation of monohaloacyl halides by the liquid phase halogenation of ketenes. More particularly. this invention relates to the halogenation of ketenes in the presence ofa solvent or a reaction medium that inhibits or prevents the formatior of polyhaloacyl halides and minimizes the formation of acyl halides. The term halogenating agent as used herein includes chlorine. bromine. iodine. and halogen halides such as iodine monochloride. iodine monobromide. bromine monochloride and the like.

The liquid phase halogenation of ketene is well known but the previously known methods of conducting this reaction have resulted in the formation of monohaloacetyl halides contaminated with a considerable proportion of dihaloacetyl halides and polyhalogenated by-products. These earlier methods utilized such solvents as chlorinated benzenes. nitrobenzene. carbon tetrachloride. chloroacetyl chloride. acetyl chloride, l.2-dichloroethane, acetonitrile. benzonitrile, nitromethane and various other solvents. Each of these solvents had a common shortcoming; that is. they all resulted in the formation of a considerable amount of dihaloacetyl halide. together with the desired product. monohaloacetyl halide. In some of these solvents, the undesired trihaloacetyl halides were also formed. The dihalo derivatives have no commercial utility and their separation from the monohalo derivative is expensive and time consuming. For example. dichloroacetyl chlo ride has a boiling point of approximately lU7C whereas monochloroacetyl chloride has a boiling point of about 105C. This proximity of the boiling points of these two compounds renders their separation exceed ingly difficult and also adds an expensive and uneconomical step to the halogenation process when utilized in the previously known solvents.

The monohaloacyl halides produced by the process of this invention are valuable intermediates in the production of herbicidal alpha-haloacetanilides and other products. By contrast. the corresponding di and trihaloacyl halides have no commercial significance. In other words. they are present merely as diluents which detract from the efficacy of the commercially valuable monohaloacyl halides. The severity of the problem is evidenced by the fact that all commercially available chloroacetyl chloride is contaminated with appreciable amounts of dichloroacetyl chloride. and in some instances the dichloroacetyl chloride content is as great as six percent.

In accordance with the present invention. the disadvantages of the prior art solvents are overcome by the halogenation of a ketenc in the presence of a sulfone of the formula ll S-R ll 0 wherein R and R are each independently selected from alkyl of from I through 8 carbons. inclusive. eycloalkyl of from 5 through 6 carbons. inclusive. phenyl. substituted phenyl and substituted alkyl or R and R when taken together are alkylene of the empirical formula C,,H wherein n is an integer from 3 through 10 inclusivc. and having from 3 through 8 carbons. inclusive, in a continuous chain.

A preferred substituted alkyl group has the formula x"2x v+ l 'y wherein R'- is halo. phenyl. or substituted phenyl. x is an integer front 1 through 8. inclusive. and y is an integer from I through 3. inclusive. It is more preferred that when R is phenyl then y is l and when .t is l and v is 3 then R is halo.

A preferred substituted phenyl group has the formula wherein each Z is independently halo. trihalomethyl. cyano. nitro. lower alkyl or lower alkoxy. and m is an integer from 1 through 3. inclusive. provided that when each Z is nitro, m cannot exceed 2. Preferred Z groups are halo. nitro. lower alkyl. trifluoromethyl and lower alkoxy.

As employed herein. the terms lower alkyl and lower alkoxy" designate those groups wherein the aliphatic chain is straight or branched and has from l through 5 carbons inclusive.

The term halo" designates a halogen atom selected from fluorine. chlorine. bromine and iodine.

The process of the present invention encompasses the halogenation of ketenc. i.e.. CH. .=C=O. as well as substituted ketenes. such as methyl ketcne. dimethyl ketene. ethyl ketene. diethyl ketene. phenyl ketene. diphenyl ketene and the like.

In carrying out the process of the present invention. the ketene and the halogenating agent are introduced into the solvent medium where they react to form monohaloacyl halides which are separated from the re action medium by conventional means such as distillation. preferably at reduced pressure. The process is amenable to either continuous or to batch type operation. The operating conditions under which the reaction is conducted are not critical but it is preferred to maintain them within specified limits to maximize the yield of the monohaloacyl halides. ln essence. it is only necessary that the reaction mass is liquid under reaction conditions. Because of practical consideration. however. the reaction is normally conducted within the approximate temperature range of 50C to lS()C. preferably from 0C to l5(lC. at a pressure from about 50 mm. of Hg to about 2 atmospheres. In most instances. however. it is more preferred to operate in a continuous mode at a temperature between about 0C and about 1 lOC at a pressure between about mm. and about 760 mm. In a batch process it is more preferred to operate in this temperature range at a pressure between about 50 mm. and 760 mm. The reaction of the halogenating agent and the ketene will progress to form substantially pure monohaloacyl halides regardless of the mole ratio of the reactants. The advantages of the present invention are more fully realized. however. when the mole ratio of halogenating agent to ketene is maintained between about 0.811 and about 2.0:1 and optimum results are obtained with mole ratios of halogenating agent to ketene between about l:l and about l.3:l. The presence of a sulfone of the present invention in the reaction mass minimizes the forma tion of undesired acyl halides and particularly minimizes the formation of dihaloacyl halides and other polyhalogenated by-products.

ln accordance with the present invention, the sulfone 4 utes. the addition of the reactants was terminated. At the termination of the reaction, the ratio of the solvent to the sum of the solvent and product was about 0.52. The reaction mixture contained essentially sulfone,

can constitute substantially all or only a minor portion chloroacetyl chloride (HALOACYL CHLORIDE) and of the reaction medlum- The benefits of the Presem acetyl chloride. The reaction rniiture contained slightly vention are most pronounced when the solvent ratio is l h 2% f di hl i hl id (D1HALOA high but substantial benefits are realized even when the CYL HAUDE) d other h1 i d b Sulfhhe is present in relatively Small amounts- The products. Analysis of the fractionated reaction mixture desirable polyhalogenated acyl halides are formed only i() h d h b t 169 grams f Solvent were present n minute amounts even when the reaction muss This man recoverability of solvent indicated that chlowins a low of Selvem and y are Substantially rination of the sulfone or other side reactions leading excluded in the higher rehos- The Weight who of the to loss of solvent did not take place during the reaction. Sulfohe [0 the Sum Of the sulfohe and the Product, Upon distillation to separate the pure chloroacety] the solvent weight ratio. can vary from about 0.051l to lfl ide h l percent i ld f m h1 about 09911- In during the normal of a ride was determined to be 93%, together with about 5% batch reaction. the sulfone weight ratio diminishes with acetyi Ch]0ride the formation of the product which becomes mixed with the solvent forming the reaction mass. As the sol- Although in this example the reaction mass was not vent weight ratio diminishes. the temperature of the reagitated. agitation is optional and can be used when action mass may be lowered below the melting point of needed depending upon the reactor design and the the sulfone while still maintaining the reaction mass in choice of reactants, i.e.. ketene and halogenating the liquid state. In the practice of the continuous proagent. When bromine is the halogenating agent, it is cess. the solvent weight ratio can be maintained coiipreferred to agitate the reaction mass but good results stunt or varied to desired levels. Adjustment of the sol are also obtained without agitation. vent weight ratio will allow flexibility in choice of reac- Following the general procedure of Example 1 but tion temperature within the desired range even with with conditions and materials changed as noted in high-melting point sulfones. Table l the indicated products are obtained. The line The invention will be more clearly understood from titles of Table l are shown in parenthesis in the descripthe following detailed description of specific examples tion of Example 1 where appropriate. thereof. In the examples and throughout the specific. in Examples 3 through 5 the yield of haloacyl halide tion allproportions are expressed in parts by weight uni igh, in. ve 90 per n nd h am nt f less otherwise indicated. dihaloacyl halide is minimized giving a haloacyl halide EXAMPLE l I purity of greater than 9? percent. In Example 2 the yield of iodoacetyl chloride is about 80-90 percent. About [69 parts (SOLVENT AMOUNT) of 1,4- Diiodoacetyl chloride is extremely unstable and theretetramethylene sulfone (SOLVENT) were charged into fore is not found in the reaction mass of Example 2. a suitable reaction vessel provided with a gas outlet. Because a number of the sulfones of this invention temperature recording means and two gas spargers are solids having melting points at or above the desired below the level of the sulfone. With the reaction vessel reaction temperature it is necessary in such instances, at about 70 mm. of Hg pressure (PRESSURE) and with when operating under batch conditions. to initiate the the reaction medium maintained at a temperature of halogenation process at a temperature sufficient to approximately 28C to 30C (TEMPERATURE), kc maintain liquidity of the reaction mass. After the reactene (KETENE) and chlorine (HALOGEN) were intion is initiated. the presence of monohaloacyl halide trodueed through separate spargers at constant and allows the reactor temperature to be lowered as desubstantially equimolar rates with the chlorine being in sired. This is illustrated in Examples 1 through 3. In a sufficient excess that a slight trace of chlorine was decontinuous mode of operation. the presence of tectable in the exhaust from the vacuum system. After monohaloacyl halide in the reaction mixture provides about 45 minutes the reactor temperature was lowered liquidity even at operating temperatures which may be to about 14C to l(i( After about 3 hours and 15 min below the melting point of the sulfone.

TABLE 1 EXAMPLP. NO. I 3 4 5 SOLVENT l.-l-tetr.inicthy lcnc lfi'pentamcthylcnc l.-l--tetrnnicth vlcnc l.-l-tctraimcth vlcnc siilfonc sulfoni: sull'one sulfonc PRhSSl'RF I00 300 atmospheric atmospheric lnim Hg: llllvlPERAlL'Rl- 5- lll 21 l-' 30 50 Ka l llzNi: Kciciic Kctcnc Methyl ketene Phciiyl kctcric HALOGEN lodiiic riioiiiichloridc (hloriiic Chlorine Chlorine sOLYt-JN'I' AMOLNI 21m iiiii isn 32 (parts) HALOGEN AMoi'N'i li as IN 2: (parts) KE'll-lNl; AMOUN l 4: 4s llll) 3i li'iartsl HALOAFYL HA1 .ll)l-. lodoacct l chloride DIHALOACYL (.hloroacctfl chloride Dichloroacet l chloride Alphachlorophcnylacetyl chloride Alpha. :ilpha-dichlorol'hc iiiiti.il lcrnpcraiiirc HI .iliiiiii I I\ limt-icd to thi tcni icraliire uilhiii .i -liorl time .iticr the reaction coinriiciicw l'l'ic llllildi \cin ieraiiirc ol .ilioiil lliilt llimcrcd l \hh tcnipcraliirc \\)|lllll .i short time .il'icr the reaction comment c l.6-hexamethylene sulfone. di-n-propyl sult'one. diisobutyl sulfone. methyl ethyl sulfone. phenyl isopropyl sulfone. cyclohexyl isobutyl sulfone. octyl isopropyl sulfone. dibenzyl sulfone and methyl chloroethyl sulfone may be substituted for l.4-tetramethylene sulfone as the solvent in Example 1 to give similar results with adjustment. as necessary, of the initial temperature to maintain the reaction mass in a liquid form.

In order to illustrate the advantage of solvents of the present invention. the procedure of the foregoing Example l was substantially duplicated using other solvents over a range of reaction pressures. Solvent Recovered is the amount of solvent found present by anal ysis after completion of the reaction. The percent yields thus obtained. together with the results of representative examples of this invention are tabulated What is claimed is:

l. A process for the preparation of a monohaloacyl halide which comprises reacting a ketenc selected from the group consisting of unsubstituted ketene. methyl 5 ketene. dimethyl ketene. ethyl ketene. dicthyl ketene. phenyl ketene and diphenyl ketene and a halogenating agent selected from the group consisting of chlorine. bromine. iodine. iodine monochloride. iodine monobromide and bromine monoehloride in the presence of a sulfone of the formula below in Table ll. 0

TABLE II Chloroucctyl Acetyl Diehloro- Solvent Reaction (hloritlc Chloride acetyl Recovered Pressure Yield Purity Yield Chloride (mm. of Hg) Sol\ent (If i (11' l ("4 Yield ()H Example I J3 97 S l 9 I00 Ethyl Acetate 88 97.8 ll L5 34 73 Ethyl Acetate J2 )6 5 3 7b atmospheric pressure Carbon 'l'etra- 4-2 ti 43 l.5 7S Chloride 1.2Dichloro- 35 53 4] 2-1 )1) ethylene Methyl Acetate '41 "-1 4 4 B8 Acetonitrilc 4h 83 47 7 on Nitromethane 4H 74 3) I3 75 n-Butyl Acetate S2 15 3 S4 n Hcxyl Acetate Xl )5 l5 4 83 Benzonitrile X7 )4 9 4 )2 By comparison of the same procedure utilizing other solvents. it is self-evident that the solvents of the present invention substantially suppress the formation of polychloroacetyl chlorides and minimize the formation of acetyl chloride. The separation of pure chloroacetyl chloride from acetyl chloride and the solvent by fractionation presents no problem because of the wide di vergence in boiling points of these compounds.

The improvement effected by the sulfones of this invention is also evidenced in the recovery of the solvent for recycle purposes. This provides greatly improved economy of operation. It is also evident from the high percent recovery of the sulfones that the bene fieial effect exerted by these solvents is due to the intrinsic nature of the chemical structure of the solvent.

The beneficial results of the present invention are ob tained in like manner with other sulfones of this invention as well as with the other aforementioned halogenating agents. Bromine can be introduced into the system as the liquid. combined with the solvent in solution. or in the gaseous state below the surface of the reaction mass. In most instances it is preferred to conduct brominations in accordance with this invention by using a solution of bromine in the solvent. When iodine monochloride is used as the halogenating agent. it can be charged into the reactor by dissolving it in the solvent and then adding the resulting solution to the systern.

Although the invention has been described with respect to specific modifications. the details thereof are not to be construed as limitations except to the extent indicated in the following claims.

wherein R and R are independently selected from alkyl of from 1 through 8 carbons. inclusive. cycloalkyl of from 5 through 6 carbons. inclusive. phenyl. substituted phenyl of the formula wherein each Z is independently halo. trihalomethyl. cyano. nitro. lower alkyl or lower alkoxy. and m is an integer from l through 3. inclusive. provided that when each Z is nitro. m cannot exceed 2. and substituted alkyl of the formula "x2xy+l"""y wherein R is halo. phenyl. or substituted phenyl of the formula 2. A process ofclaim 1 wherein R and R' are each alkyl.

3. A process ofelaim 2 wherein R and R' are each npropyl.

4. A process of claim 2 wherein R and R' are each isobutyl.

5. A process of claim 2 wherein R and R are each isopropyl,

6. A process of claim 2 wherein R is methyl and R is ethyl.

7. A process olclaim 1 wherein R is substituted pheml 8. A process of claim I wherein R is phenyl,

9. A process of claim 8 wherein R is isopropylr I0. A process of claim 1 wherein R is substituted al kyl.

ll. A process of claim I wherein R is alkyl. 12. A process of claim 1 wherein the halogenating agent is chlorine.

13. A process of claim I wherein the halogenating agent is bromine.

14. A process ofclaim 1 wherein the ketene is unsub stituted ketene,

15. A process of claim 14 wherein the halogenating agent is chlorine.

16. A process of claim 1 wherein R and R taken together are alkylene.

17. A process of claim 16 wherein the sulfone is 1,6- hexamethylene sulfonei [8. A process of claim 16 wherein the sulfone is ],5 pentamethylene sulfone.

19. A process of claim 16 wherein the solvent is l,4- tetramethylene sulfonei 20. A process of claim 16 wherein the halogenating agent is chlorine.

21. A process of claim 20 wherein the ketene is unsubstituted ketene. 

1. A PROCESS FOR THE PREPARATION OF A MONOHALOACYL HALIDE WHICH COMPRISES REACTING A KETENE SELECTED FROM THE GROUP CONSISTING OF UNSUBSTITUTED KETENE, METHYL KETENE, DIMETHYL KETENE, ETHYL KETENE, DIETHYL KETENE, PHENYL KETENE AND DIPHENYL KETENE AND A HALOGENATING AGENT SELECTED FROM THE GROUP CONSISTING OF CHLORINE, BROMINE, IODINE, IODINE MONOCHLORIDE, IODINE MONOBROMIDE AND BROMINE MONOCHLORIDE IN THE PRESENCE OF A SULFONE OF THE FORMULA
 2. A process of claim 1 wherein R and R1 are each alkyl.
 3. A process of claim 2 wherein R and R1 are each n-propyl.
 4. A process of claim 2 wherein R and R1 are each isobutyl.
 5. A process of claim 2 wherein R and R1 are each isopropyl.
 6. A process of claim 2 wherein R is methyl and R1 is ethyl.
 7. A process of claim 1 wherein R is substituted phenyl.
 8. A process of claim 1 wherein R is phenyl.
 9. A process of claim 8 wherein R1 is isopropyl.
 10. A process of claim 1 wherein R is substituted alkyl.
 11. A process of claim 1 wherein R is alkyl.
 12. A process of claim 1 wherein the halogenating agent is chlorine.
 13. A process of claim 1 wherein the halogenating agent is bromine.
 14. A process of claim 1 wherein the ketene is unsubstituted ketene.
 15. A process of claim 14 wherein the halogenating agent is chlorine.
 16. A process of claim 1 wherein R and R1 taken together are alkylene.
 17. A process of claim 16 wherein the sulfone is 1,6-hexamethylene sulfone.
 18. A process of claim 16 wherein the sulfone is 1,5-pentamethylene sulfone.
 19. A process of claim 16 wherein the solvent is 1,4-tetramethylene sulfone.
 20. A process of claim 16 wherein the halogenating agent is chlorine.
 21. A process of claim 20 wherein the ketene is unsubstituted ketene. 